A 3rd Generation Partnership Project Long Term Evolution (3GPP LTE: Rel-8 or Rel-9) system adopts Multi-Carrier Modulation (MCM) in which a single Component Carrier (CC) is divided into a plurality of frequency bands. On the other hand, a 3GPP LTE-Advanced system (hereinafter, referred to as an LTE-A system) may use CA by aggregating one or more CCs to support a broader system bandwidth than in the 3GPP LTE system. The term CA may be interchanged with carrier matching, multi-CC environment, or multi-carrier environment.
For a single-CC environment such as the LTE system, only multiplexing of UCI and data using a plurality of layers on one CC is specified.
In contrast, one or more CCs are available and the number of pieces of UCI may be multiplied by the number of used CCs. For example, a Rank Indication (RI) has 2-bit or 3-bit information in the LTE system. Since a total bandwidth can be extended to up to 5 CCs in the LTE-A system, the RI may have 15-bit information at maximum.
In this case, as large UCI as 15 bits cannot be transmitted in a UCI transmission scheme defined in the LTE system and cannot be encoded with a conventional Reed-Muller (RM) code. Accordingly, there exists a need for a new method for transmitting UCI having a large amount of information in the LTE-A system.
Moreover, the LTE system gives no regard to a precoding index, when UCI is transmitted on a PUSCH. Therefore, a method for transmitting a precoding index has not been specified.
If a precoding index associated with multiple CCs and UCI are multiplexed into a PUSCH in the CA environment, the multiple CCs increase the size of the UCI. In addition, since information about the precoding index associated with the multiple CCs is added to the UCI, the size of the UCI further increases.
However, a shortcoming with conventional methods lies in that UCI is encoded only with an RM code or an 8-bit Cyclic Redundancy Check (CRC) irrespective of the increasing size of the UCI.